When Ryuuta was 6 years old, he was attacked by a youkai. At that moment, a mysterious boy named Izumo came to his aid and exorcised the youkai. Izumo gives a promise that when Ryuuta gets strong enough to be by his side, they’ll meet again. After 10 years, their paths cross once more. But it seems like Izumo doesn’t remember Ryuuta or their promise! When a youkai threatens the village, Ryuuta tries to help but Izumo ends up getting injured. At that moment, he transfers some of his power to Ryuuta...with a kiss! Together, they exorcise the youkai, with Ryuuta vowing to protect Izumo from now on and following him on his travels! (Note: “Yokai” are supernatural spirits or monsters in Japanese folklore.)